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Cover INVENTORS AT WORK Copyright by Park & Co., Brantford, Ontario. PROFESSOR ALEXANDER GRAHAM BELL. Inventors at Work With Chapters on Discovery By George Iles Author of “Flame, Electricity and the Camera” Copiously Illustrated Publisher's emblem New York Doubleday, Page & Company 1907 Copyright, 1906, by George Iles Published October, 1906 All rights reserved, including that of translation into foreign languages, including the Scandinavian TO MY FRIEND JOSEPHUS NELSON LARNED OF BUFFALO, NEW YORK CONTENTS PAGE LIST OF ILLUSTRATIONS xiii ACKNOWLEDGMENTS xxi CHAPTER I. INTRODUCTORY 1 II. FORM Form as important as substance. Why a joist is stiffer than a plank. The girder is developed from a joist. Railroad rails are girders of great efficiency as designed and tested by Mr. P. H. Dudley 5 III. FORM CONTINUED. BRIDGES Roofs and small bridges may be built much alike. The queen-post truss, adapted for bridges in the sixteenth century, neglected for two hundred years and more. A truss replaces the Victoria Tubular Bridge. Cantilever spans at Niagara and Quebec. Suspension bridges at New York. The bowstring design is an arch disguised. Why bridges are built with a slight upward curve. How bridges are fastened together in America and in England 18 IV. FORM CONTINUED. LIGHTNESS, EASE IN MOTION Why supports are made hollow. Advantages of the arch in buildings, bridges and dams. Tubes in manifold new services. Wheels more important than ever. Angles give way to curves 39 V. FORM CONTINUED. SHIPS Ships have their resistances separately studied. This leads to improvements of form either for speed or for carrying capacity. Experiments with models in basins. The Viking ship, a thousand years old, of admirable design. Clipper ships and modern steamers. Judgment in design 52 VI. FORM CONTINUED. RESISTANCE LESSENED Shapes to lessen resistance to motion. Shot formed to move swiftly through the air. Railroad trains and automobiles of somewhat similar shape. Toothed wheels, conveyors, propellers and turbines all so curved as to move with utmost freedom 65 VII. FORM CONTINUED. ECONOMY OF LIGHT AND HEAT Light economized by rightly-shaped glass. Heat saved by well-designed conveyors and radiators. Why rough glass may be better than smooth. Light is directed in useful paths by prisms. The magic of total reflection is turned to account. Holophane Globes. Prisms in binocular glasses. Lens grinding. Radiation of heat promoted or prevented at will 72 VIII. FORM CONTINUED. TOOLS AND IMPLEMENTS Tools and implements shaped for efficiency. Edge tools old and new. Cutting a ring is easier than cutting away a whole circle. Lathes, planers, shapers, and milling machines far out-speed the hand. Abrasive wheels and presses supersede old methods. Use creates beauty. Convenience in use. Ingenuity spurred by poverty in resources 89 IX. FORM CONTINUED. ABORIGINAL ART Form in aboriginal art, as affected by materials. Old forms persist in new materials. Nature’s gifts first used as given, then modified and copied. Rigid materials mean stiff patterns. New materials have not yet had their full effect on modern design 108 X. SIZE Heavenly bodies large and small. The earth as sculptured a little at a time. The farmer as a divider. Dust and its dangers. Models may mislead. Big structures economical. Smallness of atoms. Advantages thereof. Dust repelled by light 120 [vii] [viii] XI. PROPERTIES Food nourishes. Weapons and tools are strong and lasting. Clothing adorns and protects. Shelter must be durable. Properties modified by art. High utility of the bamboo. Basketry finds much to use. Aluminium, how produced and used. Qualities long unwelcome or worthless are now gainful. Properties created at need 135 XII. PROPERTIES CONTINUED Producing more and better light from both gas and electricity. The Drummond light. The Welsbach mantle. Many rivals of carbon filaments and pencils. Flaming arcs. Tubes of mercury vapor 154 XIII. PROPERTIES CONTINUED Steel: its new varieties are virtually new metals, strong, tough, and heat resisting in degrees priceless to the arts. Minute admixtures in other alloys are most potent 163 XIV. PROPERTIES CONTINUED Glass of new and most useful qualities. Metals plastic under pressure. Non-conductors of heat. Norwegian cooking box. Aladdin oven. Matter seems to remember. Feeble influences become strong in time 180 XV. PROPERTIES CONTINUED. RADIO-ACTIVITY Properties most evident are studied first. Then those hidden from cursory view. Radio-activity revealed by the electrician. A property which may be universal, and of the highest import. Its study brings us near to ultimate explanations. Faraday’s prophetic views 197 XVI. MEASUREMENT Methods beginning in rule-of-thumb proceed to the utmost refinement. Standards old and new. The foot and cubit. The metric system. Refined measurement as a means of discovery. The interferometer measures 1 5,000,000 inch. A light-wave as an unvarying unit of length 208 XVII. MEASUREMENT CONTINUED Weight, Time, Heat, Light, Electricity, measured with new precision. Exact measurement means interchangeable designs, and points the way to utmost economies. The Bureau of Standards at Washington. Measurement in expert planning and reform 219 XVIII. NATURE AS TEACHER Forces take paths of least resistance. Accessibility decides where cities shall arise. Plants display engineering principles in structure. Lessons from the human heart, eyes, bones, muscles, and nerves. What nature has done, art may imitate,—in the separation of oxygen from air, in flight, in producing light, in converting heat into work: Lessons from lower animals. A hammer-using wasp 245 XIX. QUALIFICATIONS OF INVENTORS AND DISCOVERERS Knowledge as sought by disinterested inquirers. A plenteous harvest with few reapers. Germany leads in original research. The Carnegie Institution at Washington 267 XX. OBSERVATION What to look for. The eye may not see what it does not expect to see. Lenses reveal worlds great and small otherwise unseen. Observers of the heavens and of seashore life. Collections aid discovery. Happy accidents applied to profit. Popular beliefs may be based on truth. An engineer taught by a bank swallow 279 XXI. EXPERIMENT Newton, Watt, Ericsson, Rowland, as boys were constructive. The passion for making new things. Aid from imagination and trained dexterity. Edison tells how the phonograph was born. Telephonic messages recorded. Handwriting transmitted by electricity. How machines imitate hands. Originality in attack 299 XXII. AUTOMATICITY AND INITIATION Self-acting devices abridge labor. Trigger effects in the laboratory, the studio and the workshop. Automatic telephones. Equilibrium of the atmosphere may be easily upset 329 XXIII. SIMPLIFICATION Simplicity always desirable, except when it costs too dear. Taking direct instead of roundabout paths. Omissions may be gainful. Classification and signaling simpler than ever before 340 XXIV. THEORIES HOW REACHED AND USED Educated guessing. Weaving power. Imagination indispensable. The proving process. Theory gainfully directs both observation and experiment. Tyndall’s views. Discursiveness of Thomas Young 355 XXV. THEORIZING CONTINUED Analogies have value. Many principles may be reversed with profit. The contrary of an old method may be gainful. Judgment gives place to measurement, and then passes to new fields 366 XXVI. NEWTON, FARADAY AND BELL AT WORK Newton, the supreme generalizer. Faraday, the master of experiment. Bell, the inventor of the telephone, transmits speech by a beam of light 387 [ix] [x] [xi] XXVII. BESSEMER, CREATOR OF CHEAP STEEL. NOBEL, INVENTOR OF NEW EXPLOSIVES Bessemer a man of golden ignorances. His boldness and versatility. The story of his steel process told by himself. Nobel’s heroic courage in failure and adversity. His triumph at last. Turns an accidental hint to great profit. Inventors to-day organized for attacks of new breadth and audacity 401 XXVIII. COMPRESSED AIR An aid to the miner, quarryman and sculptor. An actuator for pumps. Engraves glass and cleans castings. Dust and dirt removed by air exhaustion. Westinghouse air-brakes and signals 417 XXIX. CONCRETE AND ITS REINFORCEMENT Pouring and ramming are easier and cheaper than cutting and carving. Concrete for dwellings ensures comfort and safety from fire. Strengthened with steel it builds warehouses, factories and bridges of new excellence 429 XXX. MOTIVE POWERS PRODUCED WITH NEW ECONOMY Improvements in steam practice. Mechanical draft. Automatic stokers. Better boilers. Superheaters. Economical condensers. Steam turbines on land and sea 446 XXXI. MOTIVE POWERS, CONTINUED. HEATING SERVICES Producer gas. Mond gas. Gas engines. Steam and gas engines compared. Diesel engine best heat motor of all. Gasoline motors. Alcohol engines. Steam and gas motors united. Heat and power production together. District steam heating. Isolated plants. Electric traction. Gas for a service of heat, light and power 457 XXXII. A FEW SOCIAL ASPECTS OF INVENTION Why cities gain at the expense of the country. The factory system. Small shops multiplied. Subdivided labor has passed due bounds and is being modified. Tendencies against centralization and monopoly. Dwellings united for new services. Self-contained houses warmed from a center. The literature of invention and discovery as purveyed in public libraries 478 INDEX 489 LIST OF ILLUSTRATIONS Professor Alexander Graham Bell Frontispiece Bell Homestead, Brantford, Ontario facing 2 Lens of ice focussing a sunbeam 5 Rubber strip suspended plank-wise and joist-wise 7 Board doubled breadthwise and edgewise 7 Telegraph poles under compression. Wires under tension 8 Rubber cylinder, flattened by compression, lengthened by tension 9 Rubber joist compressed along top, extended along bottom 10 Girder cut from joist 10 Rubber I-beam suspended flatwise and edgewise 10 Girder contours simple, built up, in locomotive draw-bars 11 Steel ore car 12 Bulb angle column, New York Subway 12 Strap rail and stringer, Mohawk & Hudson R. R., 1830 13 Plimmon H. Dudley facing 14 Dudley rails 16 Steel cross-ties and rails 17 King-post truss 18 Frames of four sides 19 Cross-section Arctic ship “Roosevelt” 20 Pair of compasses stretch a rubber strip 20 Queen-post truss 21 Upper part of roof truss, Interborough Power House, New York 21 Two queen-post trusses from a bridge 22 Palladio trusses 22 Burr Bridge, Waterford, N. Y. 23 Howe and Pratt trusses 24 Baltimore truss 25 Whipple Bridge 25 Simple cantilevers 26 [xii] [xiii] [xiv] Victoria Bridge, Montreal, original form 27 Victoria Bridge, Montreal, present form 28 Cantilever Bridge, near Quebec 29 Kentucky River Cantilever Bridge 30 Arch Bridge, Niagara Falls 31 Bowstring Bridge, Philadelphia 32 Williamsburg Bridge, New York City 33 Continuous Girder Bridge, Lachine, near Montreal 34 Rubber strip supported at 4 points, and at 2 points 34 Plate girder bridge 35 Lattice girder bridge, showing rivets 36 Bookshelf laden and unladen, showing camber 36 Pin connecting parts of bridge 37 Bridge rollers in section and in plan 38 Girder sections in various forms 39 Rubber cylinders solid and hollow compared in sag 40 Handle bar of bicycle in steel tubing 40 A sulky in steel tubing 41 Pneumatic hammer in steel tubing 41 Fishing rod in steel tubing 41 Bridge of steel pipe 41 Arch bridge of steel pipe 42 Spiral fire-lighter 42 Spiral weld steel tube 42 Largest stone arch in the world, Plauen, Germany 43 Church of St. Remy, Rheims, France 43 Curve of suspended chain 44 Dam across Bear Valley, California 44 Ferguson locking-bar 45 Hand-hole plates, Erie City water-tube boiler 46 Bullock cart with solid wheels 47 Ball thrust collar bearings 48 Rigid bearings for axles of automobiles 48 Hyatt helical roller bearing. Ditto supporting an axle 49 Treads and risers of stairs joined by curves 49 Corner Madison Square Garden, New York 50 Two pipes with funnel-shaped junction 50 Model Basin, U. S. Navy, Washington, D. C. facing 54 Viking Ship 56 Clipper ship “Young America” 58 Steamship Kaiser Wilhelm II 60 Cargo steamer 61 U. S. Torpedo-boat destroyer 62 Cross-sections of ships 63 Racing automobile. Wedge front and spokeless wheels 66 Bilgram skew gearing 67 Grain elevator 68 Robins conveying belt 68 Ewart detachable link belting 69 Curves of turbines 70 Steel vanes of windmill 70 Pelton water wheel and jet 71 Luxfer prism 74 Fresnel lens 74 Lamp and reflector a unit 75 Inverted arc-light 75 Sacramento perch totally reflected in aquarium 77 Diagram illustrating total reflection 78 Holophane globe, sections 79 [xv] Holophane globe, diffusing curves 80 Holophane globe, three varieties 80 Holophane globe, and Welsbach mantle 81 Wire shortened while original direction is resumed 81 Four mirrors reflect a ray in a line parallel to first path 82 Prisms for Zeiss binocular glasses 82 Sections for Zeiss binocular glasses 83 Tools for producing optical surfaces 84 Bi-focal lens for spectacles 85 Canadian box-stove 86 Canadian dumb-stove 86 Tubing for radiator 87 Gold’s electric heater 87 Stolp wired tube for automobiles 87 Corrugated boiler 88 Pipe allowing contraction or expansion 88 Carving chisels and gouges 90 Lathe cutters 90 Ratchet bit brace 90 Eskimo skin scraper 91 Double tool drill cutting boiler plate 91 Common drill compared with ring drill 92 Twist drill 93 How a tool cuts metal 94 Dacotah fire-drill 94 Lathe, with parts in detail 95 Compound slide rest 96 Blanchard lathe 96 Turret lathe, with side and top views 97 Ericsson’s Monitor 98 Iron planer 99 Iron shaper 99 Milling machine 100 Milling cutters with inserted teeth 100 Milling cutters executing curves 101 Emery wheels 102 Carborundum wheel edges 102 Rolls to reduce steel in thickness 104 Gourd-shaded vessel, Arkansas 108 Gourd and derived pottery forms 109 Pomo basket 109 Bilhoola basket 110 Bilhoola basket, a square inch of 111 A free-hand scroll: same as woven 111 Yokut basket bowl 112 Sampler on cardboard 115 Bark vessel and derived form in clay 115 Vase from tumulus, St. George, Utah 116 Wooden tray. Clay derivative 116 Shell vessel. Earthen derivative 116 Electric lamps in candle shapes 117 Notre Dame de Bonsecours, Montreal 118 New Amsterdam Theater, New York facing 118 Cinders large and small on hearth 120 Cube subdivided into 8 cubes 121 Cube built of 27 cubes 122 [xvi] [xvii] Two rubber strips, varying as one and three in dimensions, compared in sag 127 Air bubbles rising in oil 128 Dvorak sound-mill 132 Beam of light deflects dust 133 Dr. Carl Freiherr Auer von Welsbach facing 156 Boivin burner for alcohol 157 Alcohol lamp with ventilating hood 158 Welsbach mantle 159 Tantalum lamp 160 Tungsten lamp of Dr Kuzel 160 Hewitt mercury-vapor lamp 161 Sections Pearlite and Steel facing 164 Cleaning Cars by the “Vacuum” Method facing 164 Open hearth furnace 165 Professor Ernst Abbe facing 182 Bliss forming die 184 Bliss process of shell making 184 Mandolin pressed in aluminium 185 Pressed seamless pitcher 185 Barrel of pressed steel 185 Range front of pressed steel 186 Pressed paint tube and cover 186 Norwegian cooker 189 Aladdin oven 190 Mayer’s floating magnets 193 Alum crystal, broken and restored 194 Marble before and after deformation by pressure 195 Professor Ernest Rutherford facing 202 Professor A. A. Michelson facing 214 Michelson interferometer 215 Light-wave distorted by heated air 216 Ancient Egyptian balance 219 Rueprecht balance 220 Earnshaw compensated balance wheel 223 Riefler clock 224 Photometer 227 Compass needle deflected by electric wire 230 Compass needle deflected by electric coil 231 Maxwell galvanometer 231 Weston voltmeter 232 Micrometer caliper measuring 1⁄1000 inch 236 Plug and ring for standard measurements 237 Two lenses as pressed together by Newton 237 Newton’s rings 238 Flat jig or guide 239 Deciduous cypress 247 Deciduous cypress, hypothetical diagram 248 Section of pipe or moor grass; of bulrush 251 Human hip joint 252 Valves of veins 252 Built-up gun 253 Achromatic prisms and lens 255 Three levers 256 Arm holding ball 256 Beaver teeth 258 Narwhal with twisted tusk 259 Lower part of warrior ants’ nest, showing dome 260 [xviii] Wasp using pebble as hammer 260 Cuban firefly 263 Dr. R. S. Woodward facing 276 Perforated sails for ships 292 Edison phonograph 312 Telegraphone 314 and facing 314 Gray Telautograph 315 and facing 318 Hussey’s mower or reaper 321 Mergenthaler linotype, justifying wedges 323 Schuckers’ double-wedge justifier 324 Two wedges partly in contact, and fully in contact 325 Polarized light shows strains in glass 327 Stop-motion 330 Dexter feeding mechanism 331 Schumann’s “Traumerei” in musical score and on Pianola roll 334 Mechanism of Pianola 335 Automatic Telephone 336 and facing 336 Blenkinsop’s locomotive, 1811 345 Notes on loose cards in alphabetical order 350 Sectional bookcase, desk and drawers 351 Burke telegraphic code 353 Burke simplified telegraphic signals 354 Pupin long-distance telephony 367 Water-gauge direct and reversed 370 Thomas Alva Edison facing 374 Cube-root extractor 376 Square-root extractor 377 Sturtevant ventilating and heating apparatus 380 Bicycle suspended from axle 382 Telephones receiving sound through a beam of light 395 Selenium cylinder with reflector 398 Perforated disc yielding sound from light 399 Sir Henry Bessemer facing 402 First Bessemer converter and ladle 406 New Ingersoll coal cutter 418 Drill steels 418 Sculptor at work with Pneumatic Chisel facing 418 Haeseler air-hammer 419 Rock drill used as hammer 420 Little Giant wood-boring machine 420 Water lifted by compressed air 421 Harris system of pumping by compressed air 422 Hardie nozzle for painting by compressed air 423 Vacuum renovators for carpets and upholstery 424 Injector sand-blast, Drucklieb’s 425 Vertical receiver, inter- and outer-cooler 426 Concrete silo foundation 431 Concrete silo 432 Mansion in Concrete, Fort Thomas, Kentucky facing 432 Wall of two-piece concrete blocks 434 Ransome bar for concrete 436 Corrugated steel bar 436 Thacher bar 436 Kahn bar 437 Hennebique armored concrete girder 437 Monier netting 437 [xix] [xx] Expanded metal diamond lath 438 Tree box in expanded steel 438 Royal Bank of Canada, Havana facing 438 Lock-woven wire fabric 439 Column forms for concrete, Ingalls Building, Cincinnati 440 Section of chimney, Los Angeles, Cal. 441 Coignet netting and hook 442 Section of conduit, Newark, N. J. 442 Water culvert 443 River des Pêres Bridge, Forest Park, St. Louis 444 Memorial Bridge, Washington, D. C. 444 Francis vertical turbine wheel 446 5000 Horse-Power Allis-Chalmers Steam Engine facing 448 Smoke-jack 449 Power House, Interborough Co., New York, exterior facing 450 Schmidt superheater 451 Power House, Interborough Co., New York, interior facing 452 De Laval steam turbine, sections 453 Westinghouse-Parsons Steam Turbine facing 454 Combustible gas from a candle 458 Taylor gas-producer 460 Four-cycle gas engine 463 Fire syringe 467 Sturtevant fan wheel, without casing 472 Sturtevant Monogram exhauster and solid base heater 473 New York Central R. R. Electric Locomotive with Five-Car Train facing 476 ACKNOWLEDGMENTS Aid in writing this volume is acknowledged in the course of its chapters. The author’s grateful thanks are rendered also to Dr. L. A. Fischer, of the Bureau of Standards at Washington, who has revised the paragraphs describing the work of the Bureau; to Mr. C. R. Mann of the Ryerson Physical Laboratory, University of Chicago, who corrected the paragraphs on the interferometer; to Mr. Walter A. Mitchell, formerly of Columbia University, New York, who revised most of the chapters on measurement. Mr. Thomas E. Fant, Head of the Department of Construction and Repair at the Navy Yard, Washington, D. C., gave the picture of the model basin here reproduced. Mr. Walter Hough of the National Museum, Washington, D. C., contributed a photograph of the Pomo basket also reproduced here. Mr. John Van Vleck and Mr. Henry G. Stott of New York, Mr. George R. Prowse and Mr. Edson L. Pease of Montreal, have furnished drawings and photographs for illustrations of unusual interest. Mr. George F. C. Smillie, of the Bureau of Engraving, Washington, D. C., Mr. Percival E. Fansler, Mr. Ernest Ingersoll, and Mr. Ashley P. Peck, of New York, have read in proof parts of the chapters which follow. Their corrections and suggestions have been indispensable. Professor Bradley Stoughton, of the School of Mines, Columbia University, New York, has been good enough to contribute a brief list of books on steel, supplementing the chapter on that theme written with his revision. Had it been feasible, other chapters would have been supplemented in like manner by other teachers of mark. In 1902 the American Library Association published an annotated guide to the literature of American history, engaging forty critics and scholars of distinction, with Mr. J. N. Larned as editor. It is hoped that at no distant day guides on the same helpful plan will be issued in the field of science, duly supplemented and revised from time to time. In the present volume the author has endeavored to include in his survey the main facts to the close of May, 1906. New York, September, 1906. INVENTORS AT WORK [xxi] [xxii] [1] I CHAPTER I INTRODUCTORY nventors and discoverers are justly among the most honored of men. It is they who add to knowledge, who bring matter under subjection both in form and substance, who teach us how to perform an old task, as lighting, with new economy, or hand us gifts wholly new, as the spectroscope and the wireless telegraph. It is they who tell us how to shape an oar into a rudder, and direct a task with our brains instead of tugging at it with our muscles. They enable us to replace loss with gain, waste with thrift, weariness with comfort, hazard with safety. And, chief service of all, they bring us to understand more and more of that involved drama of which this planet is by turns the stage and the spectator’s gallery. The main difference between humanity to-day and its lowly ancestry of the tree-top and the cave has been worked out by the inventors and discoverers who have steadily lifted the plane of life, made it broader and better with every passing year. On a theme so vast as the labors of these men a threshold book can offer but a few glances at principles of moment, to which the reader may add as he pleases from observations and experiments of his own. At the outset Form will engage our regard: first, as bestowed so as to be retained by girders, trusses and bridges; next, as embodied in structures which minimize friction, such as well designed ships; or as conducing to the efficiency of tools and machines; or deciding how best heat may be radiated or light diffused. A word will follow as to modes of conferring form, the influence on form of the materials employed, and the undue vitality of old forms that should long ago have bidden us good-by. Structures alike in shape may differ in size. Bigness has its economies, and so has smallness. Both will have brief attention, with a rapid survey of new materials which enable a builder to rear towers or engines bolder in dimensions than were hitherto possible. Substance, as important as form, will next receive a glance. First a word will be said about the properties of food, raiment, shelter, weapons and tools. Then, the properties of fuels and light-givers will be considered, as steadily improved in their effectiveness. How properties are modified by heat and electricity will be remarked, with illustrations from steels of new and astonishing qualities, and from notable varieties of glass produced at Jena. A few pages will recount some of the striking phenomena of radio-activity displayed by radium, thorium and kindred substances, phenomena which are remolding the fundamental conceptions of physics and chemistry. A survey of form and properties, however cursory, must involve measurement, otherwise an inventor cannot with accuracy embody a plan in a working machine, or know exactly how strong, elastic, or conducting a rod, a wire, or a frame is. Measuring instruments will be sketched, their use delineated, and the results of precise measurement noted as an aid to the construction of modern mechanism, the interchangeability of its parts, the economy of materials and of energy in every branch of industry. Next will follow a chapter noting tasks which Nature has long accomplished, and which Art has still to perform, as in converting at ordinary temperatures within the human body fuel energy into work. Plainly, a broad field opens to future invention as it copies the function of plants and animals; functions to be first carefully observed, then explained and at last imitated with the least possible waste of effort. The equipment and the talents for invention and discovery are now touched upon. First, knowledge, especially as the fruit of disinterested inquiry; Observation, as exercised by trained intelligence calling to its aid the best modern instruments; Experiment, as an educated passion for building on original lines. Then, in the mechanical field, we bestow a few glances at self-acting machines, at the simplicity of design which makes for economy not only in building, but in operation and maintenance. Either in designing a new machine, or in reaching a great truth, such as Universal Development, there is scope for Imagination upon which we next pause for a moment. A succeeding chapter outlines how theories may be launched and tested, how analogy may yield a golden hint, the profit in rules that work both ways, or even in doing just the opposite of what has been done without question for ages past. [2] [3] Copyright, 1906, by Park & Co., Brantford, Ontario, Canada BELL HOMESTEAD, BRANTFORD, ONTARIO, CANADA. Alexander Graham Bell and his Daughter in the Foreground. Here the Telephone was Perfected in 1874. Now the Home of the Bell Telephone Memorial Association. From this brief consideration of method we now pass to a few men who have exemplified method on the loftiest plane; we come into the presence of Newton, the supreme generalizer, and observe his patience and conscientiousness, as remarkable as his resourcefulness in experiment, in mathematical analysis. Even greater in experiment, while lacking mathematical power, is Faraday, who next enlists our regard. This great man, more than any other investigator, laid the foundations of modern electrical science and art. Moreover he distinctly saw how matter might reveal itself in the ‘radiant’ condition now engaging the study of the foremost inquirers in physics. Electricity has no instrument more useful in daily life, or in pure research, than the telephone. Now follows a narration by its creator, Professor Bell, of his photophone which transmits speech by a beam of light. This recital shows us how an inventor of the first rank proceeds from one attempt to another, until his toil is crowned with success. Next we hear the story of the Bessemer process from the lips of Sir Henry Bessemer himself, affording us an insight into the methods and characteristics of a mind ingenious, versatile and bold in the highest degree. An inventor of quite other type is next introduced,—Nobel, who gave dynamite to the quarryman and miner, smokeless powder to the gunner and sportsman. His unfaltering heart, beset as he was by constant peril, marks him a hero as brave as ever fought hazardous and dreary campaigns to a victorious close. Many advances in mechanical and structural art have been won rather through a succession of attacks by one leader after another, than by a single decisive blow from a Watt or an Edison. A great band of inventors, improvers, adapters, have accomplished notable tasks with no record of such a feat as Bessemer with his converter, or Abbe with Jena glass. A brief chapter deals with some of the principal uses of compressed air, an agent of steadily increasing range. As useful, in a totally different sphere—that of building material—is concrete, especially as reinforced with steel. A sketch of its applications is offered. Then follows the theme of using fuels with economy, of obtaining from them motive powers with the least possible loss. This field is to-day attracting inventors of eminent ability, with the prospect that soon motive powers will be much cheapened, with incidental abridgment of drudgery, a new expansion of cities into the country, and the production of light at perhaps as little as one-third its present cost. A page or two are next given to a few social aspects of invention, its new aid and comfort to craftsmen, farmers, householders comparatively poor. It will appear that forces working against the undue centralization of industry grow stronger every day. A closing word gives the reader, especially the young reader, a hint or two in case he wishes to pursue paths of study the first steps of which are taken in this book. In 1900 was published the author’s “Flame, Electricity and the Camera,” in which are treated some of the principal applications of heat, electricity and photography as exemplified at the time of writing. That volume may supplement the book now in the reader’s hands. CHAPTER II FORM Form as important as substance . . . Why a joist is stiffer than a plank . . . The girder is developed from a joist . . . Railroad rails are girders of great efficiency as designed and tested by Mr. P. H. Dudley. [4] [5] O Strength and Rigidity. A lens of ice focussing a sunbeam. ne January morning in Canada I saw a striking experiment. The sun was shining from an unclouded sky, while in the shade a Fahrenheit thermometer stood at about twenty degrees below zero. A skilful friend of mine had moulded a cake of ice into a lens as large as a reading glass; tightly fastened in a wooden hoop it focussed in the open air a sunbeam so as to set fire to a sheet of paper, and char on a cedar shingle a series of zigzag lines. There, indeed, was proof of the importance of form. To have kept our hands in contact with the ice would have frozen them in a few minutes, but by virtue of its curved surfaces the ice so concentrated the solar beam as readily to kindle flame. Clearly enough, however important properties may be, not less so are the forms into which matter may be fashioned and disposed. Let us consider a few leading principles by which designers have created forms that have economized their material, time and labor, and made their work both secure and lasting. We will begin with a glance at the rearing of shelter, an art which commenced with the putting together of boughs and loose stones, and to-day requires the utmost skill both of architects and engineers. Building in its modern development owes as much to improvement in form as to the use of stronger materials, brick instead of clay, iron and steel instead of wood. A stick as cut from a tree makes a capital tent-pole, and will serve just as well to sustain the roof of a cabin. For structures so low and light it is not worth while to change the shape of a stick. By way of contrast let us glance at an office building of twenty-five stories, or the main piers of the new Quebec Bridge rising 330 feet above their copings. To compass such heights stout steel is necessary, and it must be disposed in shapes more efficient than that of a cylinder, as we shall presently see. In most cases strength depends upon form, in some cases strength has nothing whatever to do with form; if we cut an iron bar in two its cross-section of say one square inch may be round, oblong, or of other contour, while the effort required to work the dividing shears will in any case be the same. But shearing stresses, such as those here in play, are not so common or important as the tension which tugs the wires of Brooklyn Bridge, or the compression which comes upon a pillar beneath the dome of the national capitol. When we place a lintel over a door or a window, we are concerned that it shall not sag and let down the wall above it in ruin: we ensure safety from disaster by giving the lintel a suitable shape. When we build a bridge we wish its roadway to remain as level as possible while a load passes, so that no hills and hollows may waste tractive power: levelness is secured by a design which is rigid as well as strong. If a railroad has weak, yielding rails, a great deal of energy is uselessly exerted in bending the metal as the wheels pass by. A stiff rail, giving way but little, avoids this waste. To create forms which in use will firmly keep their shape is accordingly one of the chief tasks of the engineer and the architect. Rubber strip suspended plank-wise, and joist-wise. [6] [7] Plank and Joist. Girders. Board doubled breadthwise through small semi-circle AB, then edgewise through large semi-circle CD. Forms of this kind, well exemplified in the steel columns and girders of to-day, have been arrived at by pursuing a path opened long ago by some shrewd observer. This man noticed that a plank laid flatwise bent much beneath a load, but that when the plank rested on its narrow edge, joist fashion, it curved much less, or hardly at all. Thus simply by changing the position of his plank he in effect altered its form with reference to the strain to be borne, securing a decided gain in rigidity. Let us repeat his experiment, using material much more yielding than wood. We take a piece of rubber eight inches long, one inch wide and one quarter of an inch thick. Placing it flatwise on supports close to its ends we find that its own weight causes a decided sag. We next place it edgewise, taking care to keep it perpendicular throughout its length, when it sags very little. Why? Because now the rubber has to bend through an arc four times greater in radius than in the first experiment. Suppose we had a large board yielding enough to be bent double, we can see that there would be much more work in doubling it edgewise than flatwise. The rule for joists is that breadth for breadth their stiffness varies as the square of their depth, because the circle through which the bending takes place varies in area as the square of its radius. In our experiment with the rubber strip by increasing depth four-fold, we accordingly increased stiffness sixteen-fold; but the breadth of our rubber when laid as a joist is only one- fourth of its breadth taken flatwise, so we must divide four into sixteen and find that our net gain in stiffness is in this case four-fold. Telegraph poles under compression. Wires under tension. Here let us for a moment dwell upon the two opposite ways in which strength may be brought into play, as either compression or tension is resisted. An example presenting both is a telegraph pole, with well- balanced burdens of wires. Its own weight and its load of wires, compress it, as we can prove by measuring the pole as stretched upon the ground before being set in place, and then after it is erected and duly laden. Should this downward thrust be excessive, the pole would be crushed and broken down. The strung wires are not in compression, but in the contrary case of tension, and are therefore somewhat lengthened as they pass from one pole to the next. Now observe a mass first subjected to compression, and next to tension. In bearing a pound weight a rubber cylinder is compressed and protrudes; when the weight is suspended from this cylinder, the rubber is lengthened by tension. In each case the effect is vastly greater than with wood or steel, because rubber has so much less stiffness than they have. [8] [9]
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